[Mobhack]

Then the AI will happily charge Mausen over a wobbly wood bridge and lose them all.

AI coding is not at all easy. "Kewl" features that would work for humans require loads and loads of AI spaghetti, that will still leave it subject to any "gotchas" that the programmer never envisioned, or that some scenario designer neglected to allow for, or whatever. Say - a scenario with an impassable river in the middle with 1 wood bridge. AI stomps over with a maus, exit bridge, no way for the remaining mausen or any other non-swimming unit to cross. Human player would keep the behemoths on his side of the river, half-brained AI will lemming the objectives.